Various means have been used in the prior art to improve the stability of flashlamp pumped dye lasers. In the past the active lasing media comprised an organic dye dissolved in a solvent such as methanol. The dye solution is normally pumped from a tap water cooled reservoir to a transparent glass dye flow tube, which is positioned proximate to the laser flashlamp, so that light from the flashlamp can be focussed into the dye. The dye solution is then returned to the dye reservoir. A portion of the energy from the flashlamp is converted to a usable laser beam while the remainder is converted to heat and must be removed by a dye reservoir heat exchanger. In addition, in the past a second tap water cooled heat exchanger was utilized to get rid of heat absorbed by a deionized water cooling system which surrounds the flash tube. Cooling of the flash tube is necessary to prevent early life burnouts. The problem with the aforementioned prior art system of cooling was the lack of control of temperature between the dye solution and the deionized water cooling water system. It is well known in the art that these aforementioned differences in temperature produce instabilities in laser beam output, and thus dictate the use of active heating and cooling devices to maintain the temperature, individually, in each of the two fluid systems. The failure to match the temperature of the dye in the dye flow tube to that of the deionized water in the cooling jacket for the flash tube results in abrupt thermal gradients in the dye flow tube causing lens effects and reduced laser output.